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What the 5th IPCC Assessment Doesn’t Include

A heavyweight boxer in the climate change match is missing from the 5th climate assessment report released by the Intergovernmental Panel on Climate Change (IPCC) on Friday.

Permafrost, which is frozen ground that doesn’t melt during the summer, covers 24% of the land in the northern hemisphere. Permafrost acts like a massive cryogenic chamber, stabilizing tens of thousands of years of organic matter, and stores approximately 1.5 trillion tons of carbon, which is twice the amount of carbon that’s currently in our atmosphere. When the organic matter thaws, that carbon will be exposed to the elements, made available to escape into the air in the form of heat-trapping gases, with the potential to knock out our efforts to slow down global warming with a one-two punch.

This effect, called the permafrost carbon feedback, is not present in the global climate change models used to estimate how warm the earth could get over the next century. But research done in the past few years shows that leaving the permafrost effect out of the climate models results in a far more conservative estimate of how our climate will change. Scientists predict that greenhouse gas from permafrost alone could lead to an additional 1.5°F of warming by the end of this century, on top of our day-to-day human emissions.

To put that in perspective, the earth has already warmed around 1.5°F since 1901, and climate scientists suggest that we should keep global warming below 3.6°F in order to avoid a “dangerous” level of warming. The climate models used in Friday’s report, without the permafrost effect, estimate that by the end of this century we will have warmed at least 7°F if we continue “business as usual” with no efforts to reduce our fossil fuel consumption.